Differential bellows pump



Oct. 14, 1952 R. B. SAALFRANK DIFFERENTIAL BELLOWS PUMP 5 Sheets-Sheet 2Filed Feb. 4, 1949 Oct. 14, 1952 R. B. SAALFRANK DIFFERENTIAL BELLOWSPUMP 5 Sheets-Sheet 5 Filed Feb. 4, 1949 INVENTOR Oct. 14, 1952 R. B.SAALFRANK DIFFERENTIAL BELLOWS PUMP 5 Sheets-Sheet 4 Filed Feb. 4, 1949[/ATTORN EYs Oct. 14, 1952 R. B. SAALFRANK DIFFERENTIAL BELLOWS PUMP 5Sheets-Sheet 5 Filed Feb. 4, 1949 Patented Oct. 14, 1952 2,613,610DIFFERENTIAL BELLOWS PUMP Royal Bartlett Saalfrank, Gulfport, Fla.,assignor to Milton Roy Company, Philadelphia, Pa., a

corporation of Pennsylvania Application February 4, 1949, Serial No. 74,676

16 Claims. (01. 103-148) The present invention relates to bellows fluidpumps.

under intermittent conditions.

A further purpose is to permit adaptation of a metering pump dischargeto a complicated curve of varying flow with a minimum of mechanism.

A further purpose is to simplify the construction of metering pumps andavoid the necessity of employing packings.

A further purpose is to reduce the variation in pumping by meteringpumps due to wear of'moving parts.

A further purpose is to eliminate the error due to resilience of thedrive and to minimize the effect of expansion and contraction in thedrive parts. 7

A further purpose is to permit the discharge of a pump to vary markedlyaccording to a predetermined plan during the discharge cycle of thepump, for example discharging firstat a high rate for a predeterminedinterval and then at a much lower rate.

A further purpose is to permit wholly independent motion of individualpumping elements in a pumping cylinder.

A further purpose is to employ as a pump chamber the internal spaceinside connected differential bellows of different displacementcharacteristics. I

A further purpose is to employ lost motion between diiierential bellows,desirably providing lost motion which backs up on compression or onexpansion of one bellows, or on compression and expansion as required,and suitably with adjust-- ment of the lost motion.

A further purpose is to adjustably limit the expansion, contraction orboth expansion and contraction of one differential bellows withoutsimilarly limiting the other.

A further purpose is to provide heating on the Walls of the difierentialbellows opposite to the other pump chamber.

- A further purpose is to provide a'suction and a discharge cycle oneach stroke of a reciprocating operator of a differential bellows pump.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate a few only of the numerousembodiments in which my invention may appear, choosing the forms shownfrom the standpoints of convenience in illustration, satisfactoryoperation and clear demonstration of the principles involved.

55 satisfactory pump can be produced by intercon- ,to very smalldischarges, and are subject to- Figures 1 to 8 inclusive arediagrammatic axial sections of pump chambers conforming to the presentinvention, each of the views showing a different variation.

Figure 1 is a horizontal axial sectional top plan and Figures 2 to 8 arevertical axial sections.

Figure 9 is a transverse section of Figure 2 on the line 99, showing thecheck valve arrangement, and illustrating likewise the check valvearrangement in Figures 3 to 8 inclusive.

Figure 10 is a vertical axial section of a further variation. I

. Describing in illustration but not in limitation and referring to thedrawings:

In the industrial field there has been increased need recently formetering pumps which will measure fluids very precisely, and in somecases will dispense the same according to some complex predeterminedschedule, often in Very small quantities. In some instances due to thedangerous character of the materials employed, the pumps must operateat'remote locations which are not subject to examination by personnel.

Typical illustrations are in the feeding of chemicals for the purpose ofproducing reactions, the introduction of treating ingredients oradditives in industrial processes, and the application of components infood processing. The fluids pumped may be common industrial liquids,special chemical solutions or liquids, or food liquids such as oils,liquefied fats, or the like.

Conventional piston pumps, while lending themselves to metering, are notreadily applied errors through the effects of leakage of packings andwear of frictionally engaging parts. Many of such prior art pumps havealso been subject to error due to resilience of the driving parts, whichlead to variations in stroke of a character which Would be minor in manyapplications but are seriously objectionable when very accurate meteringis required.

In accordance with the present-invention, the pump is based upon theaction of oppositely moving differential bellows, which haverespectively different displacement characteristics per unit ofexpansion or contraction. Broader aspects of the diiierential bellowssubject matter are included in my application Serial No. 53,953,. filedOctober 11, 1948, for Bellows Pump, which matured into Patent No.2,578,265 on December 11, 1951.

In some cases it is very desirable to produce an accurate metering pumpwithout the expense of Y fabricating a pump cylinder of the normal type.

It has been found that for many purposes a very nesting the internalspaces Of a pair of difierential bellows, which together form a singlepump chamber.

Figure 1 illustrates, suitably in axial top plan, a difierential bellowspump having an inlet passage and an outlet passage 2! suitably atopposite ends of the pump, and extending through end plates 22 and 23 tothe interior pump chamber 24 inside aligned differential bellows 25 and26. At the adjoining ends the two bellows are secured together incoaxial alignment as by welding to a connection 21 having an internalpassage 28 which permits free flow between the respective parts of thepump chamber 24. The respective bellows in this and in each of thevarious other forms shown in the present application have differentdisplacement characteristics, that is, their displacement (internally inthis form and externally in other forms) for a given unit of contractionor expansion (for example an N inch) is difierent in the case of the twobellows, preferably by virtue of difference in diameter. The bellowswill suitably be metallic bellows of beryllium copper, bronze, stainlesssteel or the like, preferably welded together at each corrugation.Depending on whether the discharge per cycle of the pump is to be smallor large, the difference in displacement characteristics of the bellowsper unit of contraction or expansion may be very slight orcorrespondingly larger.

In the inlet and outlet passages are arranged check valves of thecharacter shown in Milton Roy Sheen U. S. Patents Nos. 2,263,429 and2,367,893. These may conveniently be any suitable type of check valves,here shown as ball u ings 31 for a reciprocatin operator 3% which issuitably attached to the connection 27 and includes a head and anoperating rod M.

In operation of the form of Figure 1 it will be seen that the entirepump chamber is provided inside the differential bellows, which areaxially aligned and connected together at their adjoining ends, andreciprocated back and forth by the operator 38. On each direction ofreciproca- Y tion one bellows is expanded as the other bellows iscompressed, the discharge stroke occurring when the bellows having thegreater displacement characteristics per unit of reciprocation iscontracting and the suction stroke occurring when it is expanding. Itwill be evident that the form of Figure 1 requires very few hightolerance parts associated with the pump chamber, so that themanufacture is greatly simplified with respect to that of piston pumps.

Figures 2 to 8 inclusive show forms in which the pump cylinder 24,instead of being internal with respect to the bellows, is external ofthe bellows in the space between the bellows and a housing of thechamber.

In all of these forms there is a housing 42'surrounding the bellows,which are preferably axial- 1y aligned therein. The housing has endplates 43 and 44 secured thereto, and the housing in each case has inletand outlet passages 20 and 2| as shown in Figure 9.

In Figure 2 the operator 38 reciprocates back and forth as in Figure 1,but in this case it is a single rod extending through an opening 45 inthe end plate 44. The bellows 25 having the higher displacement rate perunit of reciprocation is connected to the operator 38, as by securing arigid metallic head 46 on the bellows '25, for example by welding. Theoperator 33 suitably threads into the head 46 at 41, and is convenientlymade adjustable by turnin the operator to change its position at thethread 41. The bellows 25 having lower displacement per unit of motionhas freedom with respect to the bellows 25, due to the provision of alost motion connection 48 between the two bellows, consisting of acylinder 53 extending axially beyond the end wall 46 and having anannular-internal end flange 5| which engages an external stop flange 52on a lost motion nut 53 threaded at 54 on to a lost motion connectionrod 55 which is threaded at 53 into the rigid forward head 51 of thebellows 26. The head 51 is suitably joined to the bellows 26 by welding.The connection rod 55 is desirably carried out through an opening 58 inthe end plate 43 and guided at 63, so that it is accessible beyond thepump for rotation to screw the connection rod in or out of the thread 56to adjust the point of pick-up of the lost motion both from thestandpoint of contraction and expansion of the bellows 25.

In operation it will be understood that during the earlier part of thestroke the bellows 25 will move positively under the action of theoperator, while the bellows 26 will be free at this point and will onlymove to the extent that pressure or suction transmitted through thefluid causes such motion or spring action of the bellows makes it move(as in retraction). As soon, however, as the lost motion picks up, thebellows having the smaller displacement per unit reciprocation will movpositively for the rest or" the stroke in either direction. The positionof positive pick-up in both compression and expansion of the bellows 26is adjusted by rotating the rod 55.

In the form of Figure 2 the bellows having smaller displacement per unitof reciprocation responds to the motion of the bellows having thegreater displacement per unit of reciprocation prior to the take-up ofthe lost motion only by virtue of the action of the fluid tending toovercome or to cooperate with the spring of the bellows, since thebellows in itself has spring properties. In the form of Figure 3,however, in addition to the provision of a lost motion connection 3|between the two bellows, a compression spring 62 is interposed, so thatduring the period of the lost motion the bellows having the smallerdisplacement per unit of reciprocation will respond to the motion of thebellows having the greater displacement per unit of reciprocation underthe action of the spring and also under the action of the fluid but notpositively, whereas as soon as the lost motion is taken up there will bepositive response for the remainder of the particular stroke. In thisform a rigid head 63 on the bellows 26 (suitably welded thereto) carriesa lost motion cylinder 64 having an internal end flange 65. In the lostmotion cylinder a disc 36 moves back and forth. The disc is supported onan extension 6! of the operator 38. The operator is adjustably threadedat 41 in the head 46' of bellows 25 so that by rotating the operator thelost motion can be adjusted as to the position at which it loses effect.

A rigid stop 68 is threaded at 10 inv a support H on the head 43 andlimits the contraction of I stroke.

thebellows 26. The stop will normally-beset at a point near the end ofthe stroke where it can serve to eliminate the effect of elasticity inthe operator by assuring a definite stopping point. While thedifferenceaccomplished by the stop might be of the order of 0.001 of aninch in some cases, this difference is very significant in someinstances.

In the form of Figure 4 there is anadjustment provided on the expansionof the bellows 26 which tends to have the effect of removing elasticityin the suction stroke. Otherwise this form is similar to that of Figure2. The stop is provided by an adjustable stop nut 12 on the adjustmentrod 55 which engages an abutment I3 on the expansion stroke of thebellows 26 having the smaller displacement per unit of reciprocation.The lost motion in the form of Figure 4 operates like that of Figure 2.

In some instances it is desirable to avoid entirely a lost motionconnection, and to permit one bellows to be free entirely except that itis contracted by the other bellows on the forward stroke and follows theother bellows in the early stages of the suction stroke. This is shownin Figure 5 where the bellows 26 has no lost motion connection, but iscontacted by and therefore contracted by the bellows 25 after a certainamount of motion on the forward stroke of bellows 25. In this case therigid head of the bellows 26 has a boss I4 at the center which will beengaged by the bellows 25 in its forward The expansion of the bellows 25under its own spring action and under the action of the fluid is limitedby a stop similar to that shown in Figure 4.

In some instances, especially where a free bellows is used, it isdesirable to limit its motion by adjustable stops on both directions.This is shown in Figure 6 where the stop rod 55 carries an additionaladjustable stop 75 which limits the contraction of the bellows 26. Thiswill be useful to eliminate the effect of elasticity or backlash in theoperator 38, and the stop on contraction of the bellows 26 will normallybe set at a position differing by perhaps only a fraction of 0.001 of aninch from the position to which this bellows would be pushed on theforward stroke of bellows 25 except for the stop.

In some cases it is desirable to be able to adjust the position at whichthe floating bellows 26 is picked up and compressed by the drivenbellows 25. As shown in Figure 7, this is accomplished by an adjustmentI4 which in effect is the equivalent of an adjustable stop. In this casethe stop I5 applied to limit contraction has been moved to a positionwithin the bellows 26 merely to illustrate that this location isregarded as optional.

In some cases it is desirable that both bellows be driven independently,either on 180 displaced or other different cycles, so that there can beadjustment of position at any time in the cycle independently in thecase of the respective bellows. In Figure 8 the bellows 25 and 26 eachhas an operator 38' or 38 which reciprocates its rigid head I6 or 11back and forth- The operators are guided in guides I8. Each-operator isreciprocated by a pivot pin 80 on a sliding block 8I which is carried ina guideway 82 of a rocker 83 pivotally secured at 84 on an adjustmentsupport 85. At the opposite end of each rocker from the block 8| itmakes sliding pivotal connection' at 86 with a cam lever 81 having fixedpivotat 88 and having at its opposite'end a cam follower90 which followsa camtrackQI- of a suitable face cam 92 on a shaft not shown. It will beevident that the tracks on the face cams can be different and can permiteither large or slight deviations between the courses followed by thetwo bellows. Thus at one part of the cycle when bellows 25 is advancingbellows 26 can contract at the same rate or a greater or less rate, andat another time in the cycle when bellows 25 is contracting bellows 26can advance at the same rate or a greater or less rate or can evenmomentarily contract if that be desired in the particular cycle.

For adjustment purposes the adjustment support has sliding guides 93which follow stationary guideways 94. The adjustment support is movedtoward and away from the axes of the coaxial bellows as by an adjustmentscrew 95. The adjustment in effect changes the throw of the rockers andthus permits variation of the stroke of both bellows in unison. Otheradjustments may be made by changing the cams.

In some cases it is desirable to apply heat to the bellows on the sideopposite from that in contact with the pumping fluid. In Figure 5 thisis suggested by showing electric heaters 96 and 91 in the interiors ofthe bellows. Any other suitable heating or cooling means or medium maybe used.

Figure 10 illustrates a pump in which there is a suction and dischargestroke on each stroke of the operator. In this form the operator 38 isoperatively connected to the moving'end of the smaller bellows 26. Alost motion connection 98 is interposed between the small bellows 26 andthe large bellows 25, which are opposed and coaxial, and the lost motionis made adjustable by an adjustment rod I00 threaded at IOI into themovable end of the large bellows. A compression spring I02, stiff enoughto overcome any effect of the fluid, acts against the movable end of thelarge bellows from the head of the pump chamber, urging the largebellows toward maximum extension. Extension of the large bellows islimited by an adjustment nut I03 acting against a stop I04. I

In operation of this form, assuming the mechanism is in its limitingposition to the left of Figure 10, moton of the operator 38 toward theright will cause the small bellows 26 to extend, while the large bellows25 will remain stationary since the lost motion has not been taken up.This will result in a discharge by the pump chamber. As soon as the lostmotion has been taken up, the large bellows will contract, moving withthe operator 38, and since its displacement per unit of motion isgreater than that of the small bellows, suction will occur. Thus therewill be both discharge and suction on the stroke of the operator 36reciprocating toward the right.

On the motion of the operator 38 in reciprocation toward the left, thecompression spring I02 will first cause the large and small bellows tomove together, in extension of the large bellows and contraction of thesmall bellows, resulting first in discharge by the pump. As soon as thelarge bellows reaches the limit of its motion toward the left due to theaction of the nut I03 impinging against the stop I04, forward mo'tionofthe large bellows will cease and further contracclaim as new cut is:

It win be evident "that by the invention it is possible to makeadjustments which will overcome to a large extent the effects ofelasticity in the drive or back-lash in the drive.

It will also be understood that advantage can be taken of the action ofthe bellows themselves as springs due to the spring metal of which theyare made by permitting one bellows to be free and to respond to itsinternal spring action and to the action of the fluid.

It will further be evident that lost motion may be provided, inaccordance with which a certain portion of either or both strokes of oneof the bellows can be positive, while the remainder of the stroke can befree, with suitable adjustment. -It will be evident also that theresponse between one bellows and another can be controlled by anindependent spring acting between the two bellows. In the case of a freebellows or of a bellows which is partially free and partially controlledby lost motion connections, there can be adequate limitation byadjustable stops on compression or expansion or both.

It will also be evident that the individual bellows can be independentlydriven.

Advantage can also be taken of the possibility of using the interior ofthe differential bellows for the pump chamber.

the simplest form which will give consistently the type of pumpdischarge which is desired. The

stops will be adjusted to permit the required limitations on the actionof the bellows, after which the pump can be operated in the conventionalmanner of a bellows pump.

In view of my invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of myinvention without copying the structure shown, and I, therefore, claimall such insofar as they fall within the reasonable spirit and scope ofmy claims.

Having thus described my invention what I and desire to secure byLetters Pat- I. In a pump, walls forming a pump chamber including in thewalls of the pump chamber two bellows having different displacementcharacteristics per unit of motion, an operator for reciprocating one ofthe bellows back and forth, and

the other bellows being at least in part free from the one bellows,whereby the motion to the other 'bellows is imparted by fluid inthe pumpduring bellows.

including a pair of bellows having different displacementcharacteristics per unit of motion, inlet and outlet connections to thepump chamber,

3. In a pump, walls forming a pump chamber check valves in theconnections, an operator for reciprocating one of the bellows back andforth, the other bellows being free from the one bellows '8 during atleast a portion of the stroke, and a stop limiting thecontraction of theother bellows.

4. .In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of reciprocation,inlet and outlet connections to the pump chamber, check valves in theconnections, an operator for reciprocating one of the bellows back andforth, the other bellows being free from the one bellows during at leasta portion of the stroke, and a stop limiting the expansion andcontraction of the other bellows.

5. In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of motion, wallsforming inlet and outlet passages to the chamber, check valves in thepassages, an operator for reciprocating one of the bellows and lostmotion contacting surfaces between the one bellows and the other bellowswhich abut in pushing and which interconnect after relative separationof the bellows in pulling when the lost motion is taken up.

6. In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of motion, wallsforming inlet and outlet passages to the chamber, check valves in thepassages, an operator for reciprocating one of the bellows and lostmotion contacting surfaces between the one bellows and the other bellowswhich abut in pushing and which interconnect after relative separationof the bellows in pulling when the lost motion is taken up.

7. In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of motion, wallsforming inlet and outlet passages to the chamber, check valves in thepassages, an operatOr for reciprocating one of the bellows and lostmotion contact surfaces between the one bellows and the other bellowswhich abut in pushing and which interconnect after relative separationof the bellows in pulling when the lost motion is taken up.

8. In a pump, walls forming a pump chamber including a pair of bellowsin line with one another and having different displacementcharacteristics per unit of reciprocation, walls forminginlet and outletpassages to the pump chamber, check valves in the passages, an operatorfor reciprocating one of the bellows back and forth, lost motioncontacting surfaces between the one bellows and the other bellows whichabut in pushing and which interconnect after relative separation of thebellows in pulling when the lost motion is taken up, and adjustment forthe lost motion contacting surfaces which varies the amount of lostmotion.

9. In a pump, walls forming a pump chamber including a pair of bellowsin line with one another and having different displacementcharacteristics per unit of motion, walls forming inlet and outletpassages to the pump chamber, check valves in the passages, an operatorfor reciprocating one of the bellows back and forth, a lost motionconnection between the bellows and a string interposed between therespective bellows.

10. In a pump, walls forming a pump chamber including a pair of bellowsin line with one another and having different displacementcharacteristics per unit of motion, walls formin inlet and outletpassages to the pump chamber, check valves in the passages, an operatorfor reciprocating one of the bellows back and forth, a lost motionconnection between the bellows, a spring interposed between therespective connections and an adjustment for the lost motion connection.

11. In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of reciprocation,walls forming inlet and outlet passages to and from the pump chamber,check valves in the connection, an operator for reciprocating one of thebellows back and forth, lost motion contacting surfaces between the onebellows and the other bellows which abut in pushing and whichinterconnect after relative separation of the bellows in pulling whenthe lost motion is taken up and an adjustable stop for limiting thecompression of the other bellows.

12. In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of reciprocation, walls forming inlet and outlet passages to and from the pumpchamber, check valves in the connection, an operator for reciprocatingone of the bellows back and forth, lost motion contacting surfacesbetween the one bellows and the other bellows which abut in pushing andwhich interconnect after relative separation of the bellows in pullingwhen the lost motion is taken up and a stop for limiting the expansionof the other bellows.

13. In a pump, walls forming a pump chamber including a plurality ofbellows having dinerent displacement characteristics per unit ofreciprocation, means for reciprocating the bellows, means for applyingheat to the opposite side of the bellows from the pump chamber, wallsforming inlet and outlet passages to the chamber and check valves in thepassages. v

14. In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of reciprocation,there being lost motion between the respective bellows and operativeconnection in a particular position and an operator for reciprocatingthat bellows having the smaller displacement characteristic per unit ofreciprocation, whereby there is a suction and a discharge on each strokeof the operator.

15. In a pump, walls forming a pump chamber including a pair of bellowshaving different displacement characteristics per unit of reciprocation,a lost motion operative connection between the bellows, and an operatorfor reciprocating the smaller bellows, whereby there are both a suctionand discharge on each stroke of the operator.

16. In a pump, walls forming a pump chamber including opposed alignedbellows having different displacement characteristics per unit ofreciprocation, an operative lost motion connection between the bellows,a spring urging the bellows having the larger displacementcharacteristics toward extension and an operator for reciprocating thesmaller bellows.

ROYAL BARTLETT SAALFRANK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

